Summaries for Patients|4 January 2005

The summary below is from the full report titled “Comparing Self-Management of Oral Anticoagulant Therapy with Clinic Management. A Randomized Trial.” It is in the 4 January 2005 issue of Annals of Internal Medicine (volume 142, pages 1-10). The authors are B. Menéndez-Jándula, J.C. Souto, A. Oliver, I. Montserrat, M. Quintana, I. Gich, X. Bonfill, and J. Fontcuberta.

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What is the problem and what is known about it so far?

Many patients require treatment with oral anticoagulant drugs such as warfarin. Some people call these drugs “blood thinners” because they decrease blood clotting. Doctors prescribe them to prevent unwanted blood clots in blood vessels or in the heart. Taking oral blood thinners can be tricky because the correct dose is different for every person and can change over time in the same person. The correct dose means that the blood is anticoagulated enough to prevent clots, but not so much as to lead to bleeding complications. Doctors use a test called the international normalized ratio (INR) to see whether a person is taking the correct amount of oral blood thinner.

Typically, a person taking oral blood thinners goes to the doctor's office or a special anticoagulation clinic every few weeks to have his or her INR checked and the blood thinner dose adjusted. Patients find this inconvenient. Recently, a portable machine called a coagulometer has made it possible for patients to check INR values at home. It is not known whether patient self-management with the use of a home coagulometer is as safe and as effective as clinic management.

Why did the researchers do this particular study?

To find out whether patient self-management of oral anticoagulation was as effective and as safe as clinic management.

Who was studied?

737 adults who had been taking oral blood thinners for at least 3 months before entering the study.

How was the study done?

The researchers assigned patients to either self-management or clinic management. Self-management patients received training and a coagulometer so that they could check their INR values at home. A nurse led the training, which consisted of 2 two-hour sessions. Training covered the use of the coagulometer and dose selection based on INR results. Clinic-management patients visited a clinic every 4 weeks to have clinic staff check INR values and adjust blood thinner dose. When the INR value was not in the target range, clinic staff adjusted the dose of the blood thinner and the timing of the next INR test. The researchers collected INR values from both groups and interviewed all patients monthly by telephone to ask about changes in health, including bleeding or clotting problems, medication changes, and hospitalizations. After following patients for an average of 1 year, the researchers compared the numbers of in-range INR values and the complications in the 2 groups.

What did the researchers find?

The level of blood thinner control was similar in the 2 groups. However, patients in the self-management group had fewer complications than patients in the clinic-management group.

What were the limitations of the study?

The study evaluated only a single clinic, and the results for other clinics may be different.

What are the implications of the study?

Patient self-management of oral anticoagulation appears to be as effective as and safer than clinic management. Health care providers should consider patient self-management as a potential way to improve oral blood-thinner therapy.

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